Multilayer capacitor

ABSTRACT

A multilayer capacitor includes an element body, and a pair of side surfaces and a pair of main surfaces; and a pair of external electrodes. The element body includes an inner layer portion in which a plurality of internal electrodes and a plurality of dielectric layers are alternately stacked in a second direction where the pair of main surfaces face each other, and a pair of outer layer portions disposed outside the inner layer portion in the second direction. On at least one of the pair of end surfaces, the internal electrode of the inner layer portion protrudes outward in the first direction from the outer layer portion by a predetermined protrusion amount. A ratio of the protrusion amount to a dimension of the element body in the second direction ranges from 11,000 ppm to 16,000 ppm.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No.2021-032760 filed on Mar. 2, 2021, the entire contents of which areincorporated by reference herein.

TECHNICAL FIELD

The present invention relates to a multilayer capacitor.

BACKGROUND

A multilayer capacitor has been known that includes an element bodyhaving a pair of end surfaces facing each other, and a pair of sidesurfaces and a pair of main surfaces located between the pair of endsurfaces to extend in a length direction where the pair of end surfacesface each other; and a pair of external electrodes disposed on the pairof end surfaces (for example, refer to Japanese Unexamined PatentPublication No. 2003-318060). Such a multilayer capacitor includes aninner layer portion in which internal electrodes are stacked, and outerlayer portions that interpose the inner layer portion therebetween.

SUMMARY

Here, in the above-described multilayer capacitor, the internalelectrode of the inner layer portion may protrude outward in the lengthdirection from the outer layer portion by a predetermined protrusionamount. Since there is a possibility that such a protrusion amountaffects the performance of the multilayer capacitor, it is required toimprove the performance of the multilayer capacitor by adjusting theprotrusion amount within an appropriate range.

Therefore, an object of the present invention is to provide a multilayercapacitor of which the performance can be improved.

A multilayer capacitor includes an element body having a pair of endsurfaces facing each other, and a pair of side surfaces and a pair ofmain surfaces located between the pair of end surfaces to extend in afirst direction where the pair of end surfaces face each other; and apair of external electrodes disposed on the pair of end surfaces. Theelement body includes an inner layer portion in which a plurality ofinternal electrodes and a plurality of dielectric layers are alternatelystacked in a second direction where the pair of main surfaces face eachother, and a pair of outer layer portions disposed outside the innerlayer portion in the second direction. On at least one of the pair ofend surfaces, the internal electrode of the inner layer portionprotrudes outward in the first direction from the outer layer portion bya predetermined protrusion amount. A ratio of the protrusion amount to adimension of the element body in the second direction ranges from 11,000ppm to 16,000 ppm.

When the protrusion amount is too large, there is a high possibility ofthe generation of cracks, whereas when the protrusion amount is toosmall, there is a possibility that a variation in electrostaticcapacitance is affected by poor contact between the internal electrodeand the external electrode. On the other hand, as a result of earnestresearch, the inventors have reached that there is a correlation betweenthe ratio of the protrusion amount to the dimension of the element bodyin the second direction and the performance of the multilayer capacitor,and have found an appropriate range. Specifically, cracks can besuppressed by setting the ratio of the protrusion amount to thedimension of the element body in the second direction to 16,000 ppm orless. In addition, a variation in electrostatic capacitance can besuppressed by setting the ratio of the protrusion amount to thedimension of the element body in the second direction to 11,000 ppm ormore. As described above, the performance of the multilayer capacitorcan be improved.

The ratio may be 15,000 ppm or less or may be 14,000 ppm or less. Inthis case, cracks can be further suppressed.

The ratio may be 12,000 or more or may be 12,500 ppm or more. In thiscase, a variation in electrostatic capacitance can be further reduced.

The internal electrode may include a main electrode portion forming anelectrostatic capacitance, and a connecting portion that connects themain electrode portion and the external electrode, and a width dimensionof the connecting portion may be smaller than a width dimension of themain electrode portion in a third direction where the pair of sidesurfaces face each other. In this case, the infiltration of a platingsolution in the vicinity of the connecting portion can be suppressed,whereas cracks or a variation in electrostatic capacitance is likely tobe generated. On the other hand, when the ratio is set within theabove-described ranges, cracks or a variation in electrostaticcapacitance can be suppressed while the infiltration of the platingsolution is suppressed.

The present invention can provide the multilayer capacitor of which theperformance can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating a multilayer capacitoraccording to one embodiment of the present invention.

FIG. 2 is a view for describing a cross-sectional configuration of themultilayer capacitor according to the present embodiment.

FIG. 3 is a view for describing a cross-sectional configuration of themultilayer capacitor according to the present embodiment.

FIG. 4 is a view for describing a cross-sectional configuration of themultilayer capacitor according to the present embodiment.

FIG. 5 is an enlarged cross-sectional view of the vicinity of an endsurface.

FIGS. 6A and 6B are tables showing experimental conditions andmeasurement results.

FIG. 7 is a graph illustrating measurement results.

FIG. 8 is a graph illustrating measurement results.

DETAILED DESCRIPTION

Hereinafter, an embodiment of the present invention will be described indetail with reference to the accompanying drawings. Incidentally, in thedescription, the same components or components having the same functionare denoted by the same reference signs, and duplicated descriptionswill be omitted.

A configuration of a multilayer capacitor C1 according to the presentembodiment will be described with reference to FIGS. 1 to 3. FIG. 1 is aperspective view illustrating the multilayer capacitor according to thepresent embodiment. FIGS. 2 and 3 are views for describingcross-sectional configurations of the multilayer capacitor according tothe present embodiment. In the present embodiment, the multilayercapacitor C1 will be described as an example of an electronic component.

As illustrated in FIG. 1, the multilayer capacitor C1 includes anelement body 2 having a rectangular parallelepiped shape, and anexternal electrode 5 and an external electrode 7 disposed on outersurfaces of the element body 2. The external electrode 5 and theexternal electrode 7 are separated from each other. The rectangularparallelepiped shape includes a rectangular parallelepiped shape ofwhich corners and ridge line portions are chamfered, and a rectangularparallelepiped shape of which corners and ridge line portions arerounded. The external electrodes 5 and 7 are also terminal electrodes.

The element body 2 has a pair of end surfaces 2 a and 2 b facing eachother, a pair of main surfaces 2 c and 2 d facing each other, and a pairof side surfaces 2 e and 2 f facing each other, as outer surfaces of theelement body 2. In the present embodiment, a direction where the pair ofend surfaces 2 a and 2 b face each other (first direction D1) is alength direction of the element body 2, a direction where the pair ofmain surfaces 2 c and 2 d face each other (second direction D2) is aheight direction of the element body 2, and a direction where the pairof side surfaces 2 e and 2 f face each other (third direction D3) is awidth direction of the element body 2.

A length of the element body 2 in the first direction D1 is larger thana length of the element body 2 in the second direction D2 and a lengthof the element body 2 in the third direction D3. The length of theelement body 2 in the second direction D2 and the length of the elementbody 2 in the third direction D3 are equal. Namely, in the presentembodiment, the pair of end surfaces 2 a and 2 b have a square shape,and the pair of main surfaces 2 c and 2 d and the pair of side surfaces2 e and 2 f have a rectangular shape. The length of the element body 2in the first direction D1 may be equal to the length of the element body2 in the second direction D2 and to the length of the element body 2 inthe third direction D3. The length of the element body 2 in the seconddirection D2 may be different from the length of the element body 2 inthe third direction D3.

As for being equal, in addition to being exactly equal, values includinga slight difference, a production error or the like within a range setin advance may be regarded as being equal. For example, when a pluralityof values are included within a range of ±5% of an average value of theplurality of values, the plurality of values are specified as beingequal.

The pair of main surfaces 2 c and 2 d extend in the first direction D1to connect the pair of end surfaces 2 a and 2 b. The pair of mainsurfaces 2 c and 2 d also extend in the third direction D3. The pair ofside surfaces 2 e and 2 f extend in the first direction D1 to connectthe pair of end surfaces 2 a and 2 b. The pair of side surfaces 2 e and2 f also extend in the second direction D2.

The element body 2 is configured by stacking a plurality of dielectriclayers 21 in the direction where the pair of main surfaces 2 c and 2 dface each other (second direction D2). In the element body 2, a stackingdirection of the plurality of dielectric layers 21 (hereinafter, simplyreferred to as a “stacking direction”) coincides with the seconddirection D2. Each of the dielectric layers 21 is made of, for example,a sintered body of ceramic green sheets containing a dielectric material(BaTiO₃-based, Ba(Ti, Zr)O₃-based, or (Ba, Ca)TiO₃-based dielectricceramic). In the actual element body 2, the dielectric layers 21 areintegrated to such an extent that a boundary between the dielectriclayers 21 cannot be visually recognized. The third direction D3 may bethe stacking direction.

Accordingly, the element body 2 includes an inner layer portion 20 inwhich a plurality of internal electrodes 11, a plurality of internalelectrodes 13, and the plurality of dielectric layers 21 are stackedwith each other in the second direction D2. In addition, the elementbody 2 includes a pair of outer layer portions 22 disposed outside theinner layer portion 20 in the second direction D2. Accordingly, theinner layer portion 20 is interposed between the pair of outer layerportions 22 in the second direction D2. Incidentally, a material formingthe outer layer portion 22 may be different from a material forming theinner layer portion 20. In the case of being different, the generationof cracks by a difference in thermal shrinkage rate between the innerlayer portion 20 and the outer layer portion 22 can be suppressed in thepresent embodiment, so that the effect becomes remarkable.Alternatively, the outer layer portion 22 may be made of the samematerial as that of the inner layer portion 20. Even when the materialsof the outer layer portion 22 and the inner layer portion 20 are thesame, a structure such as a thickness of the sheet or the presence orabsence of the electrodes may contribute to the difference in shrinkagerate between the outer layer portion 22 and the inner layer portion 20.

As illustrated in FIGS. 2 and 3, the multilayer capacitor C1 includesthe plurality of internal electrodes 11 and the plurality of internalelectrodes 13. The internal electrodes 11 and 13 are made of aconductive material (for example, Ni, Cu or the like) that is usuallyused as an internal conductor of a multilayer electronic component. Theinternal electrodes 11 and 13 are formed as a sintered body of aconductive paste containing the above conductive material. The internalelectrodes 11 and 13 function as internal conductors that are disposedinside the element body 2.

The internal electrode 11 and the internal electrode 13 are disposed atdifferent positions (layers) in the second direction D2. Namely, theinternal electrodes 11 and the internal electrodes 13 are alternatelydisposed to face each other at intervals in the second direction D2inside the element body 2. The internal electrode 11 and the internalelectrode 13 have different polarities.

As illustrated in FIG. 3, each of the internal electrodes 11 includes amain electrode portion 11 a and a connecting portion 11 b. The mainelectrode portion 11 a is a portion that faces a main electrode portion13 a of the internal electrode 13 to be described later to form anelectrostatic capacitance. The connecting portion 11 b is a portion thatconnects the main electrode portion 11 a and the external electrode 5.The connecting portion 11 b extends from one side (one short side) ofthe main electrode portion 11 a to be exposed on the end surface 2 a.The internal electrode 11 is exposed on the end surface 2 a, but is notexposed on the end surface 2 b, the pair of main surfaces 2 c and 2 d,and the pair of side surfaces 2 e and 2 f. The main electrode portion 11a and the connecting portion 11 b are integrally formed.

The main electrode portion 11 a has a rectangular shape having the firstdirection D1 as a long side direction and having the third direction D3as a short side direction. Namely, the main electrode portion 11 a ofeach of the internal electrodes 11 has a larger length in the firstdirection D1 than a length in the third direction D3. The connectingportion 11 b extends from an end portion on an end surface 2 a side ofthe main electrode portion 11 a to the end surface 2 a. A length of theconnecting portion 11 b in the first direction D1 is smaller than alength of the main electrode portion 11 a in the first direction D1. Alength of the connecting portion 11 b in the third direction D3 is equalto a length of the main electrode portion 11 a in the third directionD3. The connecting portion 11 b is connected to the external electrode 5at an end portion exposed on the end surface 2 a. The length of theconnecting portion 11 b in the third direction D3 may be smaller thanthe length of the main electrode portion 11 a in the third direction D3.

As illustrated in FIG. 3, each of the internal electrodes 13 includesthe main electrode portion 13 a and a connecting portion 13 b. The mainelectrode portion 13 a is a portion that faces the main electrodeportion 11 a of the internal electrode 11 to be described later to forman electrostatic capacitance. The connecting portion 13 b is a portionthat connects the main electrode portion 13 a and the external electrode7. The main electrode portion 13 a faces the main electrode portion 11 ain the second direction D2 with a part of the element body 2 (dielectriclayer) therebetween. The connecting portion 13 b extends from one side(one short side) of the main electrode portion 13 a to be exposed on theend surface 2 b. The internal electrode 13 is exposed on the end surface2 b, but is not exposed on the end surface 2 a, the pair of mainsurfaces 2 c and 2 d, and the pair of side surfaces 2 e and 2 f. Themain electrode portion 13 a and the connecting portion 13 b areintegrally formed.

The main electrode portion 13 a has a rectangular shape having the firstdirection D1 as a long side direction and having the third direction D3as a short side direction. Namely, the main electrode portion 13 a ofeach of the internal electrodes 13 has a larger length in the firstdirection D1 than a length in the third direction D3. The connectingportion 13 b extends from an end portion on an end surface 2 b side ofthe main electrode portion 13 a to the end surface 2 b. A length of theconnecting portion 13 b in the first direction D1 is smaller than alength of the main electrode portion 13 a in the first direction D1. Alength of the connecting portion 13 b in the third direction D3 is equalto a length of the main electrode portion 13 a in the third directionD3. The connecting portion 13 b is connected to the external electrode 7at an end portion exposed on the end surface 2 b. The length of theconnecting portion 13 b in the third direction D3 may be smaller thanthe length of the main electrode portion 13 a in the third direction D3.

Incidentally, the internal electrodes 11 and 13 may have the shapeillustrated in FIG. 4. The internal electrodes 11 and 13 illustrated inFIG. 4 have a shape in which the connecting portions 11 b and 13 b arenarrowed with respect to the main electrode portions 11 a and 13 a.Accordingly, a width dimension of the connecting portion 11 b is smallerthan a width dimension of the main electrode portion 11 a in the thirddirection D3. A width dimension of the connecting portion 13 b issmaller than a width dimension of the main electrode portion 13 a in thethird direction D3.

The external electrode 5 is located at an end portion on the end surface2 a side of the element body 2 when viewed in the first direction D1.The external electrode 5 includes an electrode portion 5 a located onthe end surface 2 a; an electrode portion 5 b located on the pair ofmain surfaces 2 c and 2 d; and an electrode portion 5 c located on thepair of side surfaces 2 e and 2 f. Namely, the external electrode 5 isformed on five surfaces 2 a, 2 c, 2 d, 2 e, and 2 f.

The electrode portions 5 a, 5 b, and 5 c adjacent to each other areconnected to each other at ridge line portions of the element body 2,and are electrically connected to each other. The electrode portion 5 aand the electrode portion 5 b are connected to each other at the ridgeline portion between the end surface 2 a and each of the main surfaces 2c and 2 d. The electrode portion 5 a and the electrode portion 5 c areconnected to each other at the ridge line portion between the endsurface 2 a and each of the side surfaces 2 e and 2 f.

The electrode portion 5 a is disposed to cover all portions of theconnecting portions 11 b which are exposed on the end surface 2 a, andthe connecting portions 11 b are directly connected to the externalelectrode 5. Namely, the connecting portions 11 b connect the mainelectrode portions 11 a and the electrode portion 5 c. Accordingly, eachof the internal electrodes 11 is electrically connected to the externalelectrode 5.

The external electrode 7 is located at an end portion on the end surface2 b side of the element body 2 when viewed in the first direction D1.The external electrode 7 includes an electrode portion 7 a located onthe end surface 2 b; an electrode portion 7 b located on the pair ofmain surfaces 2 c and 2 d; and an electrode portion 7 c located on thepair of side surfaces 2 e and 2 f. Namely, the external electrode 7 isformed on five surfaces 2 b, 2 c, 2 d, 2 e, and 2 f.

The electrode portions 7 a, 7 b, and 7 c adjacent to each other areconnected to each other at ridge line portions of the element body 2,and are electrically connected to each other. The electrode portion 7 aand the electrode portion 7 b are connected to each other at the ridgeline portion between the end surface 2 b and each of the main surfaces 2c and 2 d. The electrode portion 7 a and the electrode portion 7 c areconnected to each other at the ridge line portion between the endsurface 2 b and each of the side surfaces 2 e and 2 f.

The electrode portion 7 a is disposed to cover all portions of theconnecting portions 13 b which are exposed on the end surface 2 b, andthe connecting portions 13 b are directly connected to the externalelectrode 7. Namely, the connecting portions 13 b connect the mainelectrode portions 13 a and the electrode portion 7 c. Accordingly, eachof the internal electrodes 13 is electrically connected to the externalelectrode 7.

FIG. 5 is an enlarged cross-sectional view of the vicinity of the endsurface 2 a. Incidentally, FIG. 5 illustrates only one end surface 2 a,but the following description is also valid for the other end surface 2b. As illustrated in FIG. 5, the internal electrode 11 of the innerlayer portion 20 protrudes outward in the first direction from the outerlayer portion 22 by a predetermined protrusion amount β. Incidentally,when reference lines ST1 and ST2 that determine the protrusion amount βare set, the reference line ST1 is set at an outermost portion of theend surface 2 a on an inner layer portion 20 side in the first directionD1. In addition, the reference line ST2 is set at an outermost portionof the end surface 2 a on a pair of outer layer portions 22 side in thefirst direction D1. Incidentally, a length of the outer layer portion 22in the first direction D1 is indicated by a dimension α. The dimension αis substantially the same as a dimension L to be described later.

Next, a dimensional relationship of the multilayer capacitor C1 will bedescribed. As illustrated in FIG. 2, the length of the element body 2 inthe first direction D1 is defined as a dimension L1. A size of a gap inthe first direction D1 between the internal electrode 11 and the endsurface 2 b, and a size of a gap in the first direction D1 between theinternal electrode 13 and the end surface 2 a are defined as a dimensionLGap. The dimension L may be set to a range of 370 to 6,100 μm andpreferably to a range of 1,450 to 3,600 μm. Incidentally, the dimensionL is a dimension in reference to outermost portions of the end surfaces2 a and 2 b in the first direction D1. The dimension LGap may be set toa range of 30 to 280 μm and preferably to a range of 100 to 200 μm.Incidentally, a dimension R that is a radius of curvature of rounding ofeach corner of the element body 2 may be set to a range of 10 to 350 μmand preferably to a range of 75 to 200 μm.

A height of the element body 2 in the second direction D2 is defined asa dimension T. A size of a gap in the second direction D2 between theinner layer portion 20 and each of the main surfaces 2 c and 2 d,namely, a thickness of the outer layer portion 22 in the seconddirection D2 is defined as a dimension TGap. The dimension T may be setto a range of 170 to 3,100 μm and preferably to a range of 600 to 2,900μm. The dimension TGap may be set to a range of 20 to 240 μm andpreferably to a range of 90 to 200 μm.

As illustrated in FIG. 3, a width of the element body 2 in the thirddirection D3 is defined as a dimension W. A size of a gap in the thirddirection D3 between the main electrode portions 11 a and 13 a of theinternal electrodes 11 and 13 and the side surfaces 2 e and 2 f isdefined as a dimension WGap. A size of a gap in the third direction D3between the connecting portions 11 b and 13 b of the internal electrodes11 and 13 and the side surfaces 2 e and 2 f is defined as a dimensionW2Gap. Incidentally, a width of each of the connecting portions 11 b and13 b is defined as a dimension WD. The dimension W may be set to a rangeof 170 to 5,400 μm and preferably to a range of 600 to 2,900 μm. Thedimension WGap may be set to a range of 30 to 280 μm and preferably to arange of 100 to 200 μm. The dimension W2Gap may be set to a range of 30to 700 μm and preferably to a range of 230 to 560 μm.

As illustrated in FIG. 4, a thickness of the dielectric layer 21 isdefined as a dimension t1, and a thickness of each of the internalelectrodes 11 and 13 is defined as a dimension t2. The dimension t1 maybe set to a range of 0.6 to 6.5 μm and preferably to a range of 1.6 to2.2 μm. The dimension t2 may be set to a range of 0.6 to 1.2 μm andpreferably to a range of 0.8 to 1.0 μm.

Next, a magnitude of the protrusion amount p of the inner layer portion20 will be described. The magnitude of the protrusion amount β isaffected by an overall size of the multilayer capacitor C1 and the like.Therefore, here, a preferable range of the protrusion amount β will bedescribed using a ratio of the protrusion amount β to a dimension of apredetermined portion of the multilayer capacitor C1. In addition, therange of the ratio of the protrusion amount β is set to a range wherethe generation of thermal cracks in a base material of the element body2 can be suppressed and a variation in electrostatic capacitance can besuppressed. In the multilayer capacitor C1, a desired protrusion amountβ can be obtained by adjusting firing conditions such as a maximumtemperature during firing, the thickness of the internal electrodes 11and 13, or the like. Therefore, even when the multilayer capacitors C1have the same shape and size, samples having different protrusionamounts β can be fabricated by changing firing conditions, the thicknessof the internal electrodes 11 and 13, or the like.

In the specification, generation of thermal cracks was evaluated asfollows. A plurality (for example, 20) of samples of the multilayercapacitors C1 having the same shape and size and having the sameprotrusion amount β were prepared. Then, each sample was immersed in asolder bath at 400° C. for 3 seconds, and was taken out. Then, a test ofresistance against cracks caused by thermal stress was performed. Eachsample was observed after the test to evaluate a ratio of the number ofthe samples having thermal cracks to the total number. In FIGS. 6A and6B, the ratio is indicated by % in a “thermal crack” item, and FIGS. 7and 8, the ratio is indicated by “base material thermal crack %”.Incidentally, a method for evaluating thermal cracks is not necessarilylimited to the above-described method.

In the specification, a variation in electrostatic capacitance wasevaluated as follows. A plurality (for example, 10) of samples of themultilayer capacitors C1 having the same shape and size and having thesame protrusion amount β were prepared. Then, each sample was measuredfor electrostatic capacitance. After the electrostatic capacitances ofall the samples were acquired, an average value was calculated. Then, aCV value was calculated by dividing a standard deviation by the averagevalue, and the CV value was evaluated as a variation. In FIGS. 6A and6B, the value is shown in a “capacitance value” item, and in FIGS. 7 and8, the value is indicated by “electrostatic capacitance CV”.Incidentally, a method for evaluating a variation in electrostaticcapacitance is not necessarily limited to the above-described method.

Specifically, here, as a result of earnest research, the inventors havefound that a predetermined relationship is established between a ratioof the protrusion amount β to the dimension T of the element body 2 inthe second direction D2 (hereinafter, may be referred to as a “Tratio”), and the generation of thermal cracks. Incidentally, the T ratiois a value obtained by a calculation formula such as “protrusion amountβ/T dimension”. Specifically, as illustrated in FIG. 7, the basematerial thermal crack is suppressed to 0% in a region where the T ratiois small. In addition, the ratio of the base material thermal crackincreases proportionally as the T ratio increases along a predeterminedapproximate line AL1 in a region where the T ratio is large. Thevariation in electrostatic capacitance decreases as the T ratioincreases along a predetermined approximate line AL2 in a region wherethe T ratio is small. In addition, the variation in electrostaticcapacitance converges to a predetermined value (vicinity of 0.008 CV inFIG. 7) in a region where the T ratio is large, and is suppressed to thevicinity of the value.

Further, as a result of earnest research, the inventors have found thata predetermined relationship is established between a ratio of theprotrusion amount β to the dimension TGap of one outer layer portion 22in the second direction D2 (hereinafter, may be referred to as a “TGapratio”), and the generation of thermal cracks. Incidentally, the TGapratio is a value obtained by a calculation formula such as “protrusionamount β/TGap dimension”. Specifically, as illustrated in FIG. 8, thebase material thermal crack is suppressed to 0% in a region where theTGap ratio is small. In addition, the ratio of the base material thermalcrack increases proportionally as the TGap ratio increases along apredetermined approximate line AL3 in a region where the TGap ratio islarge. The variation in electrostatic capacitance decreases as the TGapratio increases along a predetermined approximate line AL4 in a regionwhere the TGap ratio is small. In addition, the variation inelectrostatic capacitance converges to a predetermined value (vicinityof 0.008 CV in FIG. 8) in a region where the TGap ratio is large, and issuppressed to the vicinity of the value.

FIGS. 7 and 8 are graphs obtained by performing experiments according toexperimental conditions shown in FIGS. 6A and 6B. Incidentally,conditions of the multilayer capacitor C1 are not limited to those shownin FIGS. 6A and 6B. Namely, since the numerical value ranges describedin the specification are specified not by absolute values of theprotrusion amount β but by the ratio of the protrusion amount β, evenwhen the conditions of the multilayer capacitor are changed, the samerelationships are established. In the experiments shown in FIGS. 6A and6B, as for components A and B, the protrusion amount β was set to valuesshown in a “protrusion” item of FIG. 6A. Incidentally, the values of theabove-described “LGap” are shown in an “L” item of a “Gap dimension”column. The same applies to other items. In addition, as for a componentC, seven types of multilayer capacitors having the shape and size buthaving different protrusion amounts β were prepared (components C-1 toC-7). The T ratio was calculated from these conditions, and were shownin a “T dimension ppm” item of a “protrusion ratio” column. In addition,the TGap ratio was calculated and shown in a “lid thickness ppm” item ofthe “protrusion ratio” column. Incidentally, a ratio of the protrusionamount β to the dimension α of the length of the outer layer portion 22in the first direction D1 was shown in a “β/α ppm” item. A large numberof the components A, B, and C-1 to C-7 set to these experimentalconditions were prepared and measured for base material thermal cracksand a variation in electrostatic capacitance by the above-describedmethod. Measurement results of a variation in electrostatic capacitancewere shown in a “capacitance value/CV” item, and measurement results ofbase material thermal crack were shown in a “400° C./thermal crack”item. Incidentally, in FIG. 6B, the dimension t1 of the thickness of thedielectric layer 21 was shown in “BT thickness t1”, the dimension t2 ofthe thickness of the internal electrodes 11 and 13 was shown in“electrode thickness t2”, and the layer numbers of the internalelectrodes 11 and 13 were shown in a “layer number” item. Incidentally,barium titanate, calcium titanate, strontium titanate, or the like isadopted as a main component of a material of the dielectric layer 21 ofthe inner layer portion 20 of each component, and barium titanate,calcium titanate, strontium titanate, or the like is adopted as a maincomponent of a material of the outer layer portion 22.

Specifically, the T ratio ranges preferably from 11,000 ppm to 16,000ppm. Further, the T ratio is more preferably 15,000 ppm or less andfurther preferably 14,000 ppm or less. In addition, the T ratio is morepreferably 12,000 ppm or more and further preferably 12,500 ppm or more.

In the multilayer capacitor C1, it is preferable that the generation ofbase material thermal cracks is suppressed to 20% or less. In thisregard, the generation of base material thermal cracks can be suppressedto 20% or less by setting the T ratio to 16,000 ppm or less. Forexample, in the example illustrated in FIG. 7, a measure scale of 20% isillustrated, and the 20% line and the approximate line AL1 intersectwith each other at a T ratio of approximately 16,000 ppm. Here, sincethe approximate line AL1 is a straight line that is set from a plot ofexperiment results using a known an approximation method (here, theleast squares method), the approximate line AL1 includes an error. Inaddition, the position of the approximate line AL1 may be slightlychanged depending on the approximation method. Therefore, in a range of±4% from an intersection between approximate line AL1 and an evaluationvalue line (here, 20% line) set on the vertical axis, the experimentresults can be substantially regarded as being on the evaluation line inevaluation considering an error. Incidentally, since the samedescription of dealing with an error with respect to such anintersection is valid for the following numerical value ranges, adescription will be omitted. For this reason, it is confirmed that thegeneration of base material thermal cracks can be suppressed to 20% orless by setting the T ratio to 16,000 ppm or less.

In the multilayer capacitor C1, it is more preferable that thegeneration of base material thermal cracks is suppressed to 10% or less.In this regard, the generation of base material thermal cracks can besuppressed to 10% or less by setting the T ratio to 15,000 ppm or less.For example, in the example illustrated in FIG. 7, it is confirmed thatthe generation of base material thermal cracks is suppressed to 10% orless by setting the T ratio to 15,000 ppm or less in consideration of aposition of 10% on the approximate line AL1, the above-described errorof the approximate line, and the like.

In the multilayer capacitor C1, it is more preferable that thegeneration of base material thermal cracks is suppressed to 0%. In thisregard, the generation of base material thermal cracks can be suppressedto 0% by setting the T ratio to 14,000 ppm or less. For example, in theexample illustrated in FIG. 7, it is confirmed that the generation ofbase material thermal cracks is suppressed to 0% by setting the T ratioto 14,000 ppm or less in consideration of a position of 0% on theapproximate line AL1, the above-described error of the approximate line,and the like.

In the multilayer capacitor C1, it is preferable that a variation inelectrostatic capacitance is suppressed to 0.02 CV or less. In thisregard, the variation in electrostatic capacitance can be suppressed to0.02 CV or less by setting the T ratio to 11,000 ppm or more. Forexample, in the example illustrated in FIG. 7, it is confirmed that thevariation in electrostatic capacitance is suppressed to 0.02 CV or lessby setting the T ratio to 11,000 ppm or more in consideration of aposition of 0.02 CV on the approximate line AL2, the above-describederror of the approximate line, and the like.

In the multilayer capacitor C1, it is preferable that a variation inelectrostatic capacitance is suppressed to 0.015 CV or less. In thisregard, the variation in electrostatic capacitance can be suppressed to0.015 CV or less by setting the T ratio to 12,000 ppm or more. Forexample, in the example illustrated in FIG. 7, it is confirmed that thevariation in electrostatic capacitance is suppressed to 0.015 CV or lessby setting the T ratio to 12,000 ppm or more in consideration of aposition of 0.015 CV on the approximate line AL2, the above-describederror of the approximate line, and the like.

In the multilayer capacitor C1, it is preferable that a variation inelectrostatic capacitance is suppressed to 0.01 CV or less. In thisregard, the variation in electrostatic capacitance can be suppressed to0.01 CV or less by setting the T ratio to 12,500 ppm or more. Forexample, in the example illustrated in FIG. 7, it is confirmed that thevariation in electrostatic capacitance is suppressed to 0.01 CV or lessby setting the T ratio to 12,500 ppm or more in consideration of aposition of 0.01 CV on the approximate line AL2, the above-describederror of the approximate line, and the like.

Specifically, the TGap ratio ranges preferably from 96,000 ppm to176,000 ppm. Further, the TGap ratio is more preferably 165,000 ppm orless and further preferably 154,000 ppm or less. In addition, the TGapratio is more preferably 121,000 ppm or more and further preferably137,000 ppm or more.

In the multilayer capacitor C1, it is preferable that the generation ofbase material thermal cracks is suppressed to 20% or less. In thisregard, the generation of base material thermal cracks can be suppressedto 20% or less by setting the TGap ratio to 176,000 ppm or less. Forexample, in the example illustrated in FIG. 8, it is confirmed that thegeneration of base material thermal cracks is suppressed to 20% or lessby setting the TGap ratio to 176,000 ppm or less in consideration of aposition of 20% on the approximate line AL3, the above-described errorof the approximate line, and the like.

In the multilayer capacitor C1, it is more preferable that thegeneration of base material thermal cracks is suppressed to 10% or less.In this regard, the generation of base material thermal cracks can besuppressed to 10% or less by setting the TGap ratio to 165,000 ppm orless. For example, in the example illustrated in FIG. 8, it is confirmedthat the generation of base material thermal cracks is suppressed to 10%or less by setting the TGap ratio to 165,000 ppm or less inconsideration of a position of 10% on the approximate line AL3, theabove-described error of the approximate line, and the like.

In the multilayer capacitor C1, it is more preferable that thegeneration of base material thermal cracks is suppressed to 0%. In thisregard, the generation of base material thermal cracks can be suppressedto 0% or less by setting the TGap ratio to 154,000 ppm or less. Forexample, in the example illustrated in FIG. 8, it is confirmed that thegeneration of base material thermal cracks is suppressed to 0% bysetting the TGap ratio to 154,000 ppm or less in consideration of aposition of 0% on the approximate line AL3, the above-described error ofthe approximate line, and the like.

In the multilayer capacitor C1, it is preferable that a variation inelectrostatic capacitance is suppressed to 0.035 CV or less. In thisregard, the variation in electrostatic capacitance can be suppressed to0.035 CV or less by setting the TGap ratio to 96,000 ppm or more. Forexample, in the example illustrated in FIG. 8, it is confirmed that thevariation in electrostatic capacitance is suppressed to 0.035 CV or lessby setting the TGap ratio to 96,000 ppm or more in consideration of aposition of 0.035 CV on the approximate line AL4, the above-describederror of the approximate line, and the like.

In the multilayer capacitor C1, it is preferable that a variation inelectrostatic capacitance is suppressed to 0.02 CV or less. In thisregard, the variation in electrostatic capacitance can be suppressed to0.02 CV or less by setting the TGap ratio to 121,000 ppm or more. Forexample, in the example illustrated in FIG. 8, it is confirmed that thevariation in electrostatic capacitance is suppressed to 0.02 CV or lessby setting the TGap ratio to 121,000 ppm or more in consideration of aposition of 0.02 CV on the approximate line AL4, the above-describederror of the approximate line, and the like.

In the multilayer capacitor C1, it is preferable that a variation inelectrostatic capacitance is suppressed to 0.01 CV or less. In thisregard, the variation in electrostatic capacitance can be suppressed to0.01 CV or less by setting the TGap ratio to 137,000 ppm or more. Forexample, in the example illustrated in FIG. 8, it is confirmed that thevariation in electrostatic capacitance is suppressed to 0.01 CV or lessby setting the TGap ratio to 137,000 ppm or more in consideration of aposition of 0.01 CV on the approximate line AL4, the above-describederror of the approximate line, and the like.

Next, actions and effects of the multilayer capacitor C1 according tothe present embodiment will be described.

When the protrusion amount β is too large, there is a high possibilitythat cracks are generated because of a difference in thermal shrinkagerate between the inner layer portion 20 and the outer layer portion 22,whereas when the protrusion amount β is too small, there is apossibility that a variation in electrostatic capacitance is affected bypoor contact between the internal electrodes 11 and 13 and the externalelectrodes 5 and 7 caused by layer thinning, multilayering, or the like.On the other hand, as a result of earnest research, the inventors havereached that there is a correlation between the T ratio of theprotrusion amount β to the dimension T of the element body 2 in thesecond direction D2 and the performance of the multilayer capacitor C1,and have found an appropriate range. Specifically, cracks can besuppressed by setting the T ratio of the protrusion amount β to thedimension T of the element body 2 in the second direction D2 to 16,000ppm or less. In addition, a variation in electrostatic capacitance canbe suppressed by setting the T ratio of the protrusion amount β to thedimension T of the element body 2 in the second direction D2 to 11,000ppm or more. As described above, the performance of the multilayercapacitor C1 can be improved.

The T ratio may be 15,000 ppm or less or may be 14,000 ppm or less. Inthis case, cracks can be further suppressed.

The T ratio may be 12,000 or more or may be 12,500 ppm or more. In thiscase, a variation in electrostatic capacitance can be further reduced.

In addition, as a result of earnest research, the inventors have reachedthat there is a correlation between the TGap ratio of the protrusionamount β to the dimension TGap of one outer layer portion 22 in thesecond direction D2 and the performance of the multilayer capacitor C1,and have found an appropriate range. Specifically, cracks can besuppressed by setting the TGap ratio of the protrusion amount β to thedimension TGap of one outer layer portion 22 in the second direction D2to 176,000 ppm or less. In addition, a variation in electrostaticcapacitance can be suppressed by setting the ratio of the protrusionamount β to the dimension TGap of one outer layer portion 22 in thesecond direction D2 to 96,000 ppm or more. As described above, theperformance of the multilayer capacitor C1 can be improved.

The TGap ratio may be 165,000 ppm or less or may be 154,000 ppm or less.In this case, cracks can be further suppressed.

The TGap ratio may be 121,000 or more or may be 137,000 ppm or more. Inthis case, a variation in electrostatic capacitance can be furtherreduced.

The internal electrodes 11 and 13 may include the main electrodeportions 11 a and 13 a forming electrostatic capacitances, and theconnecting portions 11 b and 13 b that connect the main electrodeportions 11 a and 13 a and the external electrodes 5 and 7. The widthdimensions of the connecting portions 11 b and 13 b may be smaller thanthe width dimensions of the main electrode portions 11 a and 13 a in thethird direction D3 where the pair of side surfaces 2 e and 2 f face eachother. In this case, the infiltration of a plating solution in thevicinity of the connecting portions 11 b and 13 b can be suppressed,whereas cracks or a variation in electrostatic capacitance is likely tobe generated. On the other hand, when the T ratio and the TGap ratio areset within the above-described ranges, cracks or a variation inelectrostatic capacitance can be suppressed while the infiltration ofthe plating solution is suppressed.

The present invention is not limited to the above-described embodiment.

In the above-described embodiment, the dimension TGap of the pair ofouter layer portions 22 have been described as being the same. However,the dimension TGap may be differ between the outer layer portion 22 onan upper side and the outer layer portion 22 on a lower side. In thiscase, in relation to the dimension TGap of at least one outer layerportion 22, the range of the TGap ratio may be included in theabove-described range. In addition, the pair of external electrodes 5and 7 are provided, and the ranges of the T ratio and the TGap ratio maybe included in the above-described ranges in at least one of theexternal electrodes 5 and 7.

In addition, according to the present invention, the range of at leastthe T ratio may be included in the above-described range, and the rangeof the TGap ratio may not be necessarily included in the above-describedrange.

[Evaluation]

The results of the experiments shown in FIGS. 6A and 6B that areperformed under the above-described experimental conditions areevaluated. Here, the component A, the component B, the component C-6,and the component C-7 are given as comparative examples, and thecomponents C-1 to C-5 are given as examples. In all the components C-1to C-5 according to the examples, the generation of thermal cracks issuppressed to 20% or less, and a variation in electrostatic capacitanceis also suppressed to 0.02 CV or less.

REFERENCE SIGNS LIST

-   -   2: element body, 5, 7: external electrode, 11, 13: internal        electrode, 11 a, 13 a: main electrode portion, 11 b, 13 b:        connecting portion, 20: inner layer portion, 22: outer layer        portion, C1: multilayer capacitor.

What is claimed is:
 1. A multilayer capacitor comprising: an elementbody having a pair of end surfaces facing each other, and a pair of sidesurfaces and a pair of main surfaces located between the pair of endsurfaces to extend in a first direction where the pair of end surfacesface each other; and a pair of external electrodes disposed on the pairof end surfaces, wherein the element body includes an inner layerportion in which a plurality of internal electrodes and a plurality ofdielectric layers are alternately stacked in a second direction wherethe pair of main surfaces face each other, and a pair of outer layerportions disposed outside the inner layer portion in the seconddirection, on at least one of the pair of end surfaces, the internalelectrode of the inner layer portion protrudes outward in the firstdirection from the outer layer portion by a predetermined protrusionamount, and a ratio of the protrusion amount to a dimension of theelement body in the second direction ranges from 11,000 ppm to 16,000ppm.
 2. The multilayer capacitor according to claim 1, wherein the ratiois 15,000 ppm or less.
 3. The multilayer capacitor according to claim 1,wherein the ratio is 14,000 ppm or less.
 4. The multilayer capacitoraccording to claim 1, wherein the ratio is 12,000 ppm or more.
 5. Themultilayer capacitor according to claim 1, wherein the ratio is 12,500ppm or more.
 6. The multilayer capacitor according to claim 1, whereinthe internal electrode includes a main electrode portion forming anelectrostatic capacitance, and a connecting portion that connects themain electrode portion and the external electrode, and a width dimensionof the connecting portion is smaller than a width dimension of the mainelectrode portion in a third direction where the pair of side surfacesface each other.